HDU3853（期望）

题目很水了，但是原地打转的点……虽然不难想到这个坑，但是从数学的角度来讲期望不应该算正无穷嘛……为什么算0啊？

 const int maxn = 1e3 + ;
 const db eps = 1e-;
 int R, C;
 struct gird {
     db ori, right, down;
 }p[maxn][maxn];
 db E[maxn][maxn];

 int main() {
     while (scanf("%d %d", &R, &C) != EOF) {
         rep(i, , R) {
             rep(j, , C) {
                 scanf("%lf %lf %lf", &p[i][j].ori, &p[i][j].right, &p[i][j].down);
                 E[i][j] = ;
             }
         }
         irep(i, R, ) {
             irep(j, C, ) {
                 if (i == R && j == C)    continue;
                 if (fabs( - p[i][j].ori) < eps)    continue;
                 if (i < R)    E[i][j] += E[i + ][j] * p[i][j].down;
                 if (j < C)    E[i][j] += E[i][j + ] * p[i][j].right;
                 E[i][j] += ;
                 E[i][j] /= ( - p[i][j].ori);
             }
         }
         printf("%.3lf\n", E[][]);
     }
     return ;
 }